package com.ly.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.ly.dto.Result;
import com.ly.dto.UserDTO;
import com.ly.entity.Follow;
import com.ly.entity.User;
import com.ly.mapper.FollowMapper;
import com.ly.service.IFollowService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.ly.service.IUserService;
import com.ly.utils.UserHolder;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class FollowServiceImpl extends ServiceImpl<FollowMapper, Follow> implements IFollowService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private IUserService userService;

    /**
     * （根据isFollow）关注/取关用户
     * @param followUserId
     * @param isFollow
     * @return
     */
    @Override
    public Result follow(Long followUserId, Boolean isFollow) {
        // 获取登录用户
        Long userId = UserHolder.getUser().getId();

        // 判断是关注还是取关操作
        if(isFollow){
            // 执行关注操作
            Follow follow = new Follow();
            follow.setUserId(userId);
            follow.setFollowUserId(followUserId);
            boolean isSuccess = save(follow);
            if(isSuccess){
                // 写入redis的set集合: sadd userId followUserId
                String key = "follows:" + userId;
                stringRedisTemplate.opsForSet().add(key, followUserId.toString());
            }

        }else {
            // 执行取关操作 delete from tb_follow where user_id = ? and follow_user_id = ?
            boolean isSuccess = remove(new QueryWrapper<Follow>()
                    .eq("user_id", userId)
                    .eq("follow_user_id", followUserId)
            );

            if(isSuccess){
                // 移除redis的set集合数据： srem userId followUserId
                String key = "follows:" + userId;
                stringRedisTemplate.opsForSet().remove(key, followUserId.toString());
            }

        }

        return Result.ok();
    }

    /**
     * 查询是否已经关注
     * @param followUserId
     * @return
     */
    @Override
    public Result isFollow(Long followUserId) {
        // 获取登录用户
        Long userId = UserHolder.getUser().getId();

        // 查询是否关注 select * from tb_follow where user_id = ? and follow_user_id = ?
        Integer count = query().eq("user_id", userId).eq("follow_user_id", followUserId).count();

        // 若关注了返回true
        return Result.ok(count > 0);
    }


    /**
     * 查询共同关注
     * @param id
     * @return
     */
    @Override
    public Result followCommons(Long id) {
        // 获取当前用户
        Long userId = UserHolder.getUser().getId();

        // 求交集
        String key = "follows:" + userId;
        String key2 = "follows:" + id;
        // 得到的 intersect 是共同关注的用户id集合
        Set<String> intersect = stringRedisTemplate.opsForSet().intersect(key, key2);
        if(intersect == null || intersect.isEmpty()){
            // 无交集
            return Result.ok(Collections.emptyList());
        }

        // 解析id集合
        List<Long> ids = intersect.stream().map(Long::valueOf).collect(Collectors.toList());

        // 查询用户
        List<User> users = userService.listByIds(ids);

        // 转为DTO
        List<UserDTO> userDTOS = users.stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());

        return Result.ok(userDTOS);
    }
}
